What are the different types of carotid artery occlusions and how can they be identified using Doppler ultrasound?

The occlusion of the common carotid artery always leads to the occlusion of the internal carotid artery.
The reverse flow pattern can be seen in a small group of patients with common carotid artery occlusion.
The Doppler color or power can show the location of a residual channel in a vessel that was thought to be occluded.
The presence of a residual lumen in a vessel with high-grade stenosis is not a concern for clinical relevance.
a) I and III are correct.
b) II and IV are correct.
c) II and III are correct.
d) I and IV are correct.